Solving the fly-versus-drive riddle

MINNEAPOLIS - It may be the last big math problem to solve before school lets out: whether to fly or drive to that summer vacation.

It's a tricky equation, with many variables. Gas prices. Air fares. Are you going alone or with a spouse and kids? Stop at a motel or drive all night? Car rental?

Financially speaking, the most important figure is the number of travelers. Destinations that might make sense for a couple to fly to can become prohibitively expensive for a family of four or more.

If you're thinking about flying, remember you'll pay for more than just the air fare. Unless you're flying Southwest Airlines or have elite frequent-flier status, there's a good chance you'll pay baggage fees. Even with one bag per person, a $15 bag fee would add $120 to the round-trip cost for a family of four. You'll also need transportation to the airport and possibly a rental car when you get where you're going.

Of course, taking the family car isn't free either.

Gas prices have crept higher, and now average $2.23 a gallon, according to the auto club AAA. A good way to figure the total gas cost is to use the AAA's gas price calculator, at . It can figure the miles between cities, factor in the model car you'll drive and then do the math based on today's gas price. It's about as specific a gas calculation as you can get.

Don't forget to plan on food and possibly a motel along the way. Those could tip the balance back in favor of a flight, for some trips.

Besides financial variables, there's your sanity to consider, said Sally Black, who runs , which caters to traveling families. Do you like long drives? Is there a DVD player in the minivan or will you tell the kids to play the "Alphabet" game off billboards?

"Is it easier," she said, "to spend four hours with kids in an airplane, or 12 hours with kids in a minivan?"

She said she's seen the full range of penny-pinching in traveling families. Some try to sneak a 4-year-old on a flight as an infant to avoid buying a ticket. One family she knows paid to bring the au pair, and the au pair's boyfriend.

Robert Little, a financial advisor from Phoenix, wavers between driving or flying every time his family of four goes over to Disneyland in California, or for some of their trips to Rocky Point, Mexico.

"For going to the beach we can load up umbrellas and chairs and coolers and lots of swimsuits and buckets and all kinds of stuff, so there's a huge advantage there," said Little, whose children are 8 and 12.

Driving has its pitfalls, too. On a trip to Disneyland about four years ago, in the Arizona desert, 45 minutes from the nearest town, their Chevy Blazer blew a tire so violently it damaged the wheel well.

"It was fairly dangerous, July or August, 120 degrees," he said. "It was a really unpleasant experience." They thought about flying next time, but stuck with driving, especially for any trips under eight hours.

There are other choices besides flying and driving. Amtrak can be an option if you have a lot of time, and especially along the East Coast, where routes connect more big cities.

For instance, a trip from Philadelphia to Orlando in July would take almost 22 hours each way and cost $234 round trip per person.

Mapquest says that same trip would take about 16 hours by car, not counting stops. And AAA says the gas bill would be $250 in a Dodge Caravan minivan. A motel stop would run that bill up further. For one person, that might make the train a better deal. For a family of four, it wouldn't even be close, even with stops at every single Dairy Queen along the way to keep those back-seat barbarians, er, children, happy.

The bus is another option. Greyhound would make the same Philadelphia-Orlando trip in about 24 hours, for $130 round-trip. Megabus is cheap (some promotional fares are $1) but its routes are much more limited, with coverage around the upper Midwest and in the Northeast but nowhere else.